Spring counterbalance mechanism



May 21, 1963 E. T. OLSON SPRING COUNTERBALANCE MECHANISM Filed June 7,1961 FIE.

INVENTOR.

irroawar United States Patent 3,090,578 PRING COUNTERBALANCE MECHANISR iEugene T. Olson, 2905 Lincoln NE, Minneapolis, Minn- Filed June 7, 1961,Ser. No. 115,360 3 Claims. (l. 242-107.5)

This invention relates to counterbalances and more particularly to aspring counterbalance mechanism.

Some forms of counterbalance units incorporate a tension spring whichpermits only a limited distance of movement for the weight beingcounterbalanced. Others incorporate a recoil spring which allows unevencounterbalance tension throughout the travel distance of the weight.Still others incorporate a flexible cable as the tie means between theweight being counterbalanced and the counterbalance unit itself. Cablesvery often cause undesirable twisting torque of the reel it is woundupon as well as of the housing.

In addition to the undesirable twisting torque often associated with acable, there is often undesirable uneven winding of the cable upon thecounterbalance reel which may cause the cable to ultimately slide off ofthe reel surface.

It is to the elimination of the above mentioned undesirable features ofcounterbalances which the present invention is intended to overcome.Accordingly:

An object of this invention is to provide a counterbalance havingstructure and components which clumnate twisting side torques;

Another object of this invention is to provide a device of the classdescribed which is so constructed and arranged that the variations intension of the counterbalance will be minimized;

A further object of this invention is to provide adjustability forcounterbalances of difierent weights without changing of counterbalanceunits;

A still further object is to provide a reel having braces whichstabilize the reel against twisting in addition to providing a guide forthe weight strap, and other desirable features;

A further object is to provide a counterbalance which stressessimplicity of design and construction, and which lends itself easily toconstruction and repair.

These and other objects and advantages of the invention will more fullyappear from the following description, made in connection with theaccompanying drawing, wherein like reference characters refer to thesame or similar parts throughout the several views and in which:

FIGURE 1 is a perspective view of a counterbalance shown as it would bepositioned on a frame (shown in phantom drawing), and a typical weightsecured thereto (also in fantom drawing);

FIGURE 2 is an enlarged top view of FIGURE 1;

FIGURE 3 is an enlarged cross-sectional side view of FIGURE 2 taken online 3-3;

FIGURE 4 is a partial cross-sectional view of FIGURE 3 taken on line 44;and

FIGURE 5 is an enlarged perspective view of a brace as it appears on thereel discs (shown in phantom drawin Referring particularly to FIGURES 1and 2, a weight 9, typified by a block and which requirescounterbalancing, is supported by a spring counterbalance referred togenerally as which has a partially enclosing housing or cover 11, madefrom sheet material, which has formed as a part thereof its own mountingfeet 12. Mounting feet 12 in turn have mounting holes 13 for securementof the housing to a frame 14.

Shown mounted across the housing, in FIGURE 2,

is a bolt or shaft 15 having a head 16 adapted to be held ass stsPatented May 21, 1963 by a wrench. Between the head 16 and housing 11 isa washer 17. Secured upon the threaded portion 18 of shaft 15 is a nut19 which is in turn welded at 20 to a tension lever 21. Again a washer22 is interposed between the tension lever 21 and housing 11. It may bepointed out at this time that the threaded portion 18 extends only tothe washer 22 so that when the nut 19 is engaged upon the threadedportion 18 to the end of the threads, further engagement of the nut willbe prevented thus causing the shaft 15 to rotate. It is this featurewhich allows the shaft 15 to be rotated and accordingly the recoilspring tension adjusted, as will be explained subsequently.

To prevent reverse rotation of the tension lever 21 when it is undertension, a tension tie 23 is provided which is simply a band of sheetmetal, or similar structure, secured at ends 24 by a bolt and nutcombination 25 to the housing 11.

Referring now to FIGURES 3 and 4, the internal construction of thecounterbalance 10 will be explained. Rotatably secured to the shaft 15by means of bearings 26 is a reel 27. The reel in turn has a pair ofreel discs 28, which are secured to the bearings 26, and a plurality ofcontinuous brace structures 29 which define a substantially circularlyoriented supporting edge referred to generally as.30, around theperiphery of the reel discs 28. The supporting edge is defined by thechannel area 31 of the braces 29 (see FIGURE 4).

Noting FIGURES 4 and 5 particularly, the braces 29 consist of asupporting mid-portion 32 which is radially recessed with respect to thehumps 33 located at either end thereof. Humps 33 have a reverse bend 34Which interfits with the outer peripheral edge 35 of the reel discs 28.Continuous with .the humps 33 are mounting ends 36 which are welded at37 to the reel discs for positive securement thereto.

As seen in FIGURES 3 and 4, the braces 29 and reel discs 28 define anopen space 38 within which a recoil spring 39 is located and confined.It is found that when a recoil spring of steel tape, of considerablestiffness, is used, an optimum recoil characteristic is achieved whichallows substantially even tension on the reel 27 when the reel isactuated. Because of this type of material used, the recoil spring 39will have a tendency to expand outwardly and therefore rides on theinner pheriphery surface 40 of the supporting edge 30. The recoilspring, of course, is radially confined by the braces 29. The outer end41 of the recoil spring 39- is hooked about a brace for securement tothe reel. The inner end 42 is secured to the shaft 15 by means of ananchor system 43.

The anchor system consists of a pair of anchor plates or discs 44 whichhave holes 45 for interfi-tting with the shaft 15. Welded between theanchor plates, and thereto, is an anchor nut 46. Threaded through thenut and in engagement therewith is an anchor bolt 47 which is alsoprojecting through the shaft 15, as seen in FIGURE 4. The purpose ofprojecting anchor bolt 47 through the shaft is to prevent relativerotational movement between the shaft and anchor system 43. Also forminga part of the anchor system is an anchor washer 48 which is drawn intoclamping contact with the inner end 42 of the recoil spring 39 forsecurement thereto. Inner end 42 also has a hole therethrough whichanchor bolt 47 projects through.

Shown wound upon the supporting edge 39 of the reel is a weight strap 49which is secured by a hook means 50 at the inner end thereof to ananchor pin 51. The anchor pin in turn is secured across the reel discsand protrudes therethrough for positive securement thereof. The outerend of the weight strap is shown as it is protruding exteriorly of thehousing for mounting to a weight.

It will be noted at this time that the recoil spring 39 extendssubstantially the width of the inside dimension between reel discs 28.With this maximumwidth of the recoil spring, an optimum springcharacteristic may be attained. In addition there is even radial forceon the supporting edge 30 and, therefore, the recoil spring exerts notwisting torque upon the reel mechanism. The weight strap 49 is alsosubstantially the width of the channel 31. Again, by providing a wideweight strap, twisting torques are eliminated.

In the assembly of the counterbalance, a recoil spring is secured at itsinner end 42 to the anchor assembly 43. The tension lever 21 is thenrotated whereby to cause the recoil spring to 'be drawn or reeled intothe open space 38. During this assembly, the reel is held stationary andthe recoil spring is caused to feed between braces 29 into the openspace 38. When the outer end 41 of the recoil spring is drawn into theopen space 38, it is then hooked to any one of the braces 29 as shown inFIGURE 3.

With the recoil spring installed, the weight strap 49 then has the innerend thereof hooked upon the anchor pin 51 and, by continued rotation ofthe tension lever, has the full travel length of the weight strap woundupon the supporting edge. At this point the tension lever is locked inposition by the tension tie 23. It is now seen that any unreeling of theweight strap will cause increasing tension on the recoil spring, andconsequently upon the reel 27 and strap 49. If increased tension isdesired on the weight strap, the tension lever may be wound additionalturns while holding the protruding end of the weight strap stationary.

Accordingly then, a counterbalance is provided which has no twistingtorque associated therewith and, because of the components incorporated,has a substantially even tension on the weight strap through thecontemplated amount of run-out thereof. In addition, this simple designlends the counterbalance to ready adjustment for different weightswithout changing counterbalance units. Also, by incorporating bracessecured across the reel A the outer edges of said reel discs wherebysaid discs and said braces define an open space between said shaft andsaid braces, an anchor pin secured across said reel discs adjacent theouter edges thereof, a stiff but flexible metal weight strap woundexternally upon said braces having one end secured to said anchor pinand the other end protruding exteriorly of said housing in a free endadapted for attachment to a substantially heavy weight, and a stiff butflexible recoil spring wound about said shaft and secured at one endthereto and at the other end to one of said braces, said recoil springfurther being confined to said open space and further having a widthsubstantially the distance between said reel discs.

2. A spring counterbalance as set forth in claim 1 wherein said bracescomprise a continuous supporting midportion extending the distancebetween said reel discs, a hump formed at both ends of said mid-portionand interfitted with the outer edges of said reel discs, and mountingends secured to said reel discs at the outer ends of said humps, wherebysaid supporting mid-portion is radially recessed from said humps wherebyto form a channel for seating of said weight strap.

3. A spring counterbalance comprising, a housing adapted to be mountedto a frame structure, a shaft mounted across said housing, a reelrotatably secured on said shaft having two substantially circular reeldiscs secured in spaced parallel relation to said shaft by means of apair of bearings, said reel also having a plurality of flat and narrowbraces secured across the outer edges of said reel discs whereby saiddiscs and said braces define an open confinement between said shaft andsaid braces, said braces also having a radially recessed supportingmidportion when positioned across the outer edges of said discs, ananchorpin secured across said reel discs adjacent the outer edgesthereof but within said open confinement, a stiif but flexible metalstrap wound externally upon said braces within said radially recessedportion, said strap having one end secured to said anchor pin and theother discs, an additional stabilizing effect is achieved while at :thesame time providing a channel guiding means for the winding andunwinding of the weight strap.

It will, of course, be understood that various changes may bemade in theform, details, arrangements and proportions of the parts withoutdeparting from the scope of my invention as set forth in the appendedclaims.

What is claimed is:

1. A spring counterbalance comprising, a housing adapted to be mountedto a frame structure, a shaft mounted across said housing, a reelrotatably secured on said shaft and having two similar and substantiallycircular reel discs secured in spaced relation on said shaft and aplurality of flat and narrow braces secured across end'protrudingexteriorly of said housing in a free end adapted for attachment to asubstantially heavy weight, and a stiff but flexible recoil spring woundabout said shaft and secured at one end thereto and at the other end toone of said braces, said recoil spring further being confined to saidopen space and further having a width substantially the distance betweensaid reel discs.

References Cited in the file of this patent UNITED STATES PATENTS116,108 Sterns June 20, 1871 511,655 Small et al Dec. 26, 1893 532,130Woodward et al. Jan. 8, 1895 681,864 Wallace'et al; Sept. 3, 19011,105,680 Mitchell, Aug. 4, 1914- I,679,573 Hind Aug. 7, 1928 1,795,529Watson et al. Mar. 10, 1931

1. A SPRING COUNTERBALANCE COMPRISING, A HOUSING ADAPTED TO BE MOUNTEDTO A FRAME STRUCTURE, A SHAFT MOUNTED ACROSS SAID HOUSING, A REELROTATABLY SECURED ON SAID SHAFT AND HAVING TWO SIMILAR AND SUBSTANTIALLYCIRCULAR REEL DISCS SECURED IN SPACED RELATION ON SAID SHAFT AND APLURALITY OF FLAT AND NARROW BRACES SECURED ACROSS THE OTHER EDGES OFSAID REEL DISCS WHEREBY SAID DISCS AND SAID BRACES DEFINE AN OPEN SPACEBETWEEN SAID SHAFT AND SAID BRACES, AN ANCHOR PIN SECURED ACROSS SAIDREEL DISCS ADJACENT THE OUTER EDGES THEREOF, A STIFF BUT FLEXIBLE METALWEIGHT STRAP WOUND EXTERNALLY UPON SAID BRACES HAVING ONE END SECURED TOSAID ANCHOR PIN AND THE OTHER END PROTRUDING EXTERIORLY OF SAID HOUSINGIN A FREE END ADAPTED FOR ATTACHMENT TO A SUBSTANTIALLY HEAVY WEIGHT,AND A STIFF BUT FLEXIBLE RECOIL SPRING WOUND ABOUT SAID SHAFT ANDSECURED AT ONE END THERETO AND AT THE OTHER END TO ONE OF SAID BRACES,SAID RECOIL SPRING FURTHER BEING CONFINED TO SAID OPEN SPACE AND FURTHERHAVING A WIDTH SUBSTANTIALLY THE DISTANCE BETWEEN SAID REEL DISCS.